DE 10 2009 058 525 A1 describes such a fluid-tight via. A region of the flat contact has a cross-sectional contour tapered circumferentially in the axial direction. Following an encapsulation or extrusion coating of a plastic material of the plastic body onto the region of the flat contact, the flat contact is displaced in the direction of its tapering(s) against the extrusion coating. This displacement causes cavities of the encapsulated region of the flat contact to be closed along the outer surfaces of the tapered contour. The fluid-tight via is thereby sealed axially along the encapsulated region of the flat contact.
The sealing of the cavities during the displacement of the flat contact arises from contraction of the plastic material during cooling. Thermoplastic materials, in particular, change their internal structure during cooling which causes a reduction in the material volume. This after-shrinkage leads to a small gap in the flat contact which is sealed in the manner described. The attainable degree of sealing is often not sufficient under adverse environmental conditions such as high pressures and temperatures.
Challenging environmental conditions are encountered by connector parts built into vehicle transmission housings. Such connector parts are exposed to varying and high temperature differences and have to withstand vibrations and high oil pressures. In such applications, plug-in connectors with rounded pins are typically used. The round pins are inserted under high pressure into through-holes of a corresponding part. The through-holes have slightly smaller dimensions compared to the cross-sectional dimensions of the round pins.
Such a procedure is problematic when used with flat contacts instead of round pins. This is because pressure forces inside a through-hole do not act symmetrically over the surface of a flat contact. The seal in the region of the long edges of the flat contact is especially difficult to produce since the direction of the normal to the surface changes discontinuously. As a result, adequate oil tightness has not yet been achieved for transmission housing pin connectors with flat contacts for the typically encountered temperature and pressure ranges.
DE 10 2011 121 133 (corresponds to U.S. Publication No. 2014/0256167) describes a fluid-tight via whose plastic body includes a non-shrinking, duroplast material and for which the longitudinal edges of the encapsulated flat contact(s) are rounded. A fluid-tight via is thus obtained by the combination of a specifically selected encapsulation material and a specially designed flat contact(s). Both features taken together create a fluid-tight via that can even be gas-tight over a defined pressure region. Nevertheless, the gas-tight attribute is restricted to pressures that are not too high, depending on the type of gases.